Re: "failed" vs "released" and "locked-out" state and --incremental auto-re-adding

[Doug Ledford <dledford@redhat.com>]

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On 04/27/2010 06:13 AM, Christian Gatzemeier wrote:
> 
> Thanks you for responding and adding insight.
> 
> Doug Ledford <dledford <at> redhat.com> writes:
>> On 04/26/2010 06:28 PM, Christian Gatzemeier wrote:
>>> 2) To "unbind", "unlist" or "dismiss" a member from the md device stats is
>>> currently called to --remove it. In particular you can "unbind", "unlist"
>>> or "dismiss" failed or detatched members with --remove failed/detached.
>>
>> You can use --remove failed/detached/≤devname>, they all work.  But yes,
>> the underlying action here is to take an already failed device go ahead
>> and release
> 
> There we have a very good word to name --remove so that mdadm is easier to
> understand (IMHO). "release"

You're probably right, but it's also too late to change it now :-(
Remove has been in use for quite some time and there are untold numbers
of programs and scripts that use it as it is so that it would be very
difficult to change it.

>> No, and this is a safety feature.  We won't remove a good device in
>> order to prevent a typo from rendering an array dead.
> 
> I understand, makes sense to me.
> Ok, if mdadm --remove (release) could give a little hint to --fail first, if
> "device is busy", it may be able save some head scratches. ;)

Very valid request.

>>> I am unclear why --incremental seems to require a device to be
>>>  --removed (released) first
>>
>> It would be kind of useless to put that support into incremental.
>> Incremental isn't really intended to be run from the command line
>> (although you can), it's intended to be done on hotplug events.
> 
> That is exactly were I encountered this. Unplugging a failed disk, and
> plugging it back in again would fail, unless I manually --remove (released)
> the device before plugging it back in.
> 
> But I think the hot-unplugging support you added will probably fix this in
> the future even nicer. (Automatically releasing devices as soon as they are
> detached.)

Yep, the hot unplug support solves this issue quite nicely.

-- 
Doug Ledford <dledford@redhat.com>
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